Early Cenozoic Extreme Climates: The Walvis Ridge Transect

Zachos, James C; Kroon, Dick; Blum, Peter; Party, Shipboard Scientific

doi:10.2973/odp.sp.208.2002

Cited by 27 publications

(58 citation statements)

References 58 publications

(80 reference statements)

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“…All samples were freeze-dried and analysed for magnetic susceptibility per gram sediment (MS g 21 ) using an AGICO KLY-3 device. These records were compared to the split core point magnetic susceptibility (PMS) and whole core MS of the multiple sensor track (MS-MST) measurements obtained during Leg 208 13 . We converted all MS data to the MS-MST scale by performing linear regression analyses between MS g 21 and PMS ( Supplementary Fig.…”

Section: Methodsmentioning

confidence: 99%

“…We converted all MS data to the MS-MST scale by performing linear regression analyses between MS g 21 and PMS ( Supplementary Fig. 2) and the conversion of PMS to MS-MST using the equation MST ¼ ðPMS £ 2:0683Þ þ 7:8257 (R 2 ¼ 0.99) 13 .…”

Section: Methodsmentioning

confidence: 99%

“…The d 13 C bulk of Site 1263 shows the largest depletion (1.4-1.6‰), suggesting that the red clay layer at this site with the highest sedimentation rate 13 is stratigraphically the most complete and/or least affected by the dissolution of primary calcite and the presence of reworked or secondary calcite. The post-Elmo interval mirrors the typical PETM signature with an exponential recovery to pre-excursion d 13 C bulk values. The bulk carbonate oxygen isotope record (d 18 O bulk ) of Site 1263 shows a negative excursion of ,1.6‰ (Fig.…”

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confidence: 99%

“…Possible triggering mechanisms for this event include crossing a threshold temperature as the Earth warmed gradually 7 , comet impact 8 , explosive volcanism 9,10 or ocean current reorganization and erosion at continental slopes 11 , whereas orbital forcing has been excluded 12 . Here we report a distinct carbonate-poor red clay layer in deep-sea cores from Walvis ridge 13 , which we term the Elmo horizon. Using orbital tuning, we estimate deposition of the Elmo horizon at about 2 million years after the Palaeocene-Eocene thermal maximum.…”

mentioning

confidence: 99%

“…We recovered continuous, undisturbed lower Palaeogene successions at five sites along a 2-km water depth transect in multiple (mostly advanced piston core) holes. This resulted in the first complete early Palaeogene deep-sea record accumulated at relatively high sedimentation rates 13 Fig. 1) and occurs within the lower part of NP11.…”

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confidence: 99%

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Astronomical pacing of late Palaeocene to early Eocene global warming events

Lourens¹,

Sluijs

Kroon

et al. 2005

Nature

527

556

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Astronomical pacing of late Palaeocene to early Eocene global warming events

Lourens¹,

Sluijs

Kroon

et al. 2005

Nature

527

556

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Orbitally Forced Hyperstratification of the Oligocene South Atlantic Ocean

Liebrand

Raffi

Fraguas

et al. 2018

Paleoceanog and Paleoclimatol

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Pelagic sediments from the subtropical South Atlantic Ocean contain geographically extensive Oligocene ooze and chalk layers that consist almost entirely of the calcareous nannofossil Braarudosphaera . Poor recovery and the lack of precise dating of these horizons in previous studies has limited the understanding of the number of acmes, their timing and durations, and therefore their likely cause. Here we present a high‐resolution, astronomically tuned stratigraphy of Braarudosphaera oozes (29.5–27.9 Ma) from Ocean Drilling Program Site 1264 in the southeastern Atlantic Ocean. We identify seven episodes with highly abundant Braarudosphaera . Four of these acme events coincide with maxima and three with minima in the ~110 and 405‐kyr paced eccentricity cycles. The longest lasting acme event corresponds to a pronounced minimum in the ~2.4‐Myr eccentricity cycle. In the modern ocean, Braarudosphaera occurrences are limited to shallow marine and neritic settings, and the calcified coccospheres of Braarudosphaera are probably produced during a resting stage in the algal life cycle. Therefore, we hypothesize that the Oligocene acmes point to extensive and episodic (hyper) stratified surface water conditions, with a shallow pycnocline that may have served as a virtual seafloor and (partially/temporarily) prevented the coccospheres from sinking in the pelagic realm. We speculate that hyperstratification was either extended across large areas of the South Atlantic basin, through the formation of relatively hyposaline surface waters, or eddy contained through strong isopycnals at the base of eddies. Astronomical forcing of atmospheric and/or oceanic circulation could have triggered these conditions through either sustained rainfall over the open ocean and adjacent land masses or increased Agulhas Leakage.

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Kimberlite eruptions as triggers for early Cenozoic hyperthermals

Patterson

Francis

2013

Geochem Geophys Geosyst

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[1] The early Cenozoic experienced at least three short but major hyperthermals associated with disruptions of the global carbon cycle. The largest among those, the Paleocene-Eocene thermal maximum, was associated with a negative carbon isotopic excursion of~2.5% that appears to be best explained by the thermal dissociation of methane hydrates due to an initial period of warming. The cause of the initial warming has been attributed to a massive injection of carbon (CO 2 and/or CH 4 ) into the atmosphere; however, the source of the carbon is as yet unknown. The emplacement of a large cluster of kimberlite pipes at~56 Ma in the Lac de Gras region of northern Canada may have provided the carbon that triggered early warming in the form of exsolved magmatic CO 2 . Our calculations indicate that the estimated 900-1100 Pg of carbon required for the initial~3 C of ocean water warming associated with the Paleocene-Eocene thermal maximum could have been released during the emplacement of a large kimberlite cluster. The coeval ages of two other kimberlite clusters in the Lac de Gras field and two other early Cenozoic hyperthermals indicate that CO 2 degassing during kimberlite emplacement is a plausible source of the CO 2 responsible for these sudden global warming events.

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Early Cenozoic Extreme Climates: The Walvis Ridge Transect

Cited by 27 publications

References 58 publications

Astronomical pacing of late Palaeocene to early Eocene global warming events

Astronomical pacing of late Palaeocene to early Eocene global warming events

Orbitally Forced Hyperstratification of the Oligocene South Atlantic Ocean

Kimberlite eruptions as triggers for early Cenozoic hyperthermals

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